It is known to use branch vessel stent grafts deployed into vasculature of a human or animal to provide and alternate flow path where the vasculature has been damaged by accident or disease. The branch vessel stent graft allows an extension piece to be deployed from a main graft into a side vessel of the vasculature so that blood flow can enter the side vessel.
The conventional procedure to treat branch vessels utilizes a balloon expandable covered stent which is deployed through the side arm of the stent graft to connect the side vessels to a bifurcated stent graft. The limitation of a delivery system for such balloon expandable covered stents is normally 7 to 8 French which makes the design of the stent graft deployment system challenging. A further challenge is then providing a sufficient attachment between the branch vessel stent graft and the side arm of the main graft since endoleaks can occur and these are of significant concern.